A pic would be helpful, if the hole in the center has a star shape to it than it is a torx fastener (requires special tool to remove it) if it is square (it requires a special tool to remove it) but I suspect you have neither of the above I suspect you have a blind(pop) rivet. The removal of which is the discussion of many threads on this sight if it is a pop rivet it can be chisled off, the head ground off, the center drilled out with the correct sized drill bit the correct size bit is the size of the shank of the fastener if the rivet hole is not going to be reused the bit size is not so important use a bit the next size up any way there is a fair amount of work to it but doing it leads to your figuring out the easiest way for you and the swearing at it develops new vocabulary and character. Gene
Its hard to be wrong when you live in Wright City!
There is no mechanical problem that cannot be overcome by a skillfully applied combination of brute force and ignorance!